A review of primary setae and pores on legs of larval Dytiscidae (Coleoptera)

Abstract

Based on the study of 88 species of Dytiscidae, the number, shape, and position of setae and pores present on legs of first-instar larvae are described. Differences between genera, tribes, and subfamilies are emphasized. Observations from four other adephagan families are included for the establishment of the ancestral system of the family Dytiscidae. Within this family, the subfamily Hydroporinae shows the smallest deviation from the ancestral system: in Laccornis oblongus (Steph.) only the absence of a single seta on the trochanter. When possible, the ancestral setae and pores are homologized for the studied taxa. Within the Adephaga, the Dytiscidae is characterized by the presence of 10 or more primary setae on the femur and by the submedian or distal position of the first ancestral seta on the tibia. The most important characters found are presented in a dichotomous key and the polarity is determined for a set of 13 characters. The character distribution is presented and some problems with respect to phylogeny are discussed.